passing-theme-as-prop.js

// Imagine your application code looks like this

const Button = styled.button`
  color: ${props => props.theme.main};
`

const theme = {
  main: 'mediumseagreen',
}


// You can test it like this

import React from 'react';
import 'jest-styled-components';
import { shallow } from 'enzyme';

describe('<Button />', () => {
  it('applies default styles', () => {
    const theme = {
      main: 'mediumseagreen',
    }

    const wrapper = shallow(<Button theme={theme} />)

    expect(wrapper).toHaveStyleRule('main', 'mediumseagreen');
  });
});